The invention relates to a rotary tablet press comprising a rotatably driven rotor having a die plate with die bores and a plurality of upper and lower punches rotating with the die plate for producing tablets in the die bores, wherein the die plate of the rotor is assigned a deflector which deflects satisfactory tablets, which are produced in the die bores and ejected by the lower punches from the die bores, from the upper face of the die plate into a satisfactory channel, wherein in the rotational direction of the rotor a reject channel is arranged upstream of the satisfactory channel, an ejection apparatus being assigned thereto for ejecting reject or unsatisfactory tablets into the reject channel, wherein moreover a monitoring apparatus is arranged on the rotary tablet press, said monitoring apparatus monitoring at least one property of the tablets produced in the die bores and producing a reject signal for a control apparatus when the monitored property of a tablet deviates inadmissibly from a reference value, so that the control apparatus actuates the ejection apparatus for ejecting the reject tablets.
Tablets produced in the rotary tablet press are generally deflected into a satisfactory channel by means of a deflector from the die plate rotating below the deflector. The deflector may, for example, have a sickle-shaped deflection edge. Powdery material, which has been filled into the die bores of the die plate, is pressed by the upper and lower punches of a rotary tablet press in the die bores to form tablets. After the compression, the tablets are pushed by the lower punches out of the die bores toward the upper face of the die plate so that they may be deflected from the die plate by the deflector.
During the tablet production a monitoring apparatus monitors the tablets for specific parameters. For example, a pressing force measuring apparatus is able to monitor whether the pressing force which prevails during the compression of the tablet is within an admissible reference value range. If the monitoring apparatus establishes an inadmissible deviation from a reference value, it produces a reject signal which is emitted to a control apparatus, for example the machine controller of the rotary tablet press. The control apparatus then controls an ejection apparatus for targeted ejection of the rejected tablet. To this end, the ejection apparatus may be configured as an ejection nozzle which produces a puff of gas, in particular a puff of air, which blows the rejected tablet from the die plate, before reaching the deflector, into a reject channel arranged in the rotational direction of the rotor upstream of the satisfactory channel.
Such a rotary tablet press is disclosed, for example, in EP 1 688 243 B1. In this case, the tablets entering the reject channel or the satisfactory channel have to be conveyed further through the reject channel or, respectively, the satisfactory channel. To this end, in the rotary tablet press disclosed in EP 1 688 243 B1 a nozzle arrangement is provided for the reject channel and for the satisfactory channel. The nozzle arrangements produce an airflow into the reject channel or, respectively, into the satisfactory channel so that the tablets are discharged through the reject channel or, respectively, the satisfactory channel. A further nozzle arrangement is provided, said nozzle arrangement producing an airflow oriented toward a deflection portion of the deflector. The nozzle arrangements may in this case have a series of nozzle openings arranged adjacent to one another so that air mist or, respectively, an air curtain is produced. A drawback here is that the nozzle arrangements may result in tablet dust being raised and undesirable contamination of the rotary tablet press or, respectively, the surroundings.
It is known from U.S. Pat. No. 8,801,416 A to discharge tablets produced in a tablet press by vacuum apparatuses. In this case, tablets are initially supplied from the die plate to a tablet reservoir as a result of gravity. From this tablet reservoir the tablets are then conveyed further by a vacuum apparatus. A drawback here is that when the press stops, for example, loose tablets may remain on the die plate. These loose tablets may collide with subsequently produced tablets when the pressing operation then starts up again due to their inertia and lead to a back-up of tablets. Moreover, a construction comprising a tablet reservoir is costly.